Cow power could light homes

Cow manure could be used to power up to 3% of North America's electricity needs and slash greenhouse gas emissions, researchers have claimed.

In an article published in the Institute of Physics’ Environmental Research Letters, a team from the US say their work is the first attempt to outline a procedure for quantifying the national amount of renewable energy that could be produced by livestock herds.

Cow Power: The Energy and Emissions Benefits of Converting Manure to Biogas recommends using anaerobic digestion to turn manure into biogas which standard microturbines can use to produce electricity.

Manure left to decompose naturally emits two of the most potent greenhouse gases – nitrous oxide and methane, both of which are many times more harmful than headline-grabbing CO2.

But the researchers from the University of Texas said using it as biogas has the potential to reduce the US’ net GHG emissions by 99m metric tonnes – wiping out about 4% of the country’s emissions from electricity production.

The current livestock population in the US could produce about 100bn kW hours of electricity, they said.

Authors of the paper Dr. Michael Webber and Amanda Cuellar said: “In light of the criticism that has been levelled against biofuels, biogas production from manure has the less-controversial benefit of reusing an existing waste source and has the potential to improve the environment.

“Nonetheless, the logistics of widespread biogas production, including feedstock and digestates transportation, must be determined at the local level to produce the most environmentally advantageous, economical, and energy efficient system.”

They admit that the burning of biogas would lead to the emissions of some CO2, but argued the output from biogas-burning plants would be less than that from coal.

Kate Martin

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